Paper cutter is a common tool for cutting one or more pieces of paper into specified sizes efficiently. A conventional paper cutter has a rail with one fixed end pivotally secured onto the bed and one free end. A slider carrying a cutting blade can slide along the rail. While using such paper cutter, the rail is lifted up by exerting a force on the free end with the fixed end as a fulcrum. Then, the paper to be cut is placed under the rail, lying on the bed. By putting the rail down and exerting a depressing force on the rail, the paper holding plate mounted to the rail urges the paper against the bed. When the cutting blade is carried by the slider to travel on the paper clamped between the paper holding plate and the bed, the paper is cut into pieces. Since the paper is secured between the paper holding plate and the bed by way of user's depressing force, it is laboring and hard to assure of well positioning of the paper. The problem is more serious when a pile of paper is simultaneously cut. The pile of paper to be cut may not be well aligned, and in practice, the topmost sheet may slightly deviate from the others when the rail is put down to rest on the topmost sheet of paper. Hence, it is difficult to cut the paper into desired sizes accurately.
For solving this problem, an improved paper cutter is proposed by Mori in U.S. Pat. No. 5,287,783. As illustrated in FIGS. 1(a) and 1(b), the schematic diagrams show the appearance and the inner structure of this paper cutter. The paper cutter mainly comprises a bed 10, a rail 11, and a slider 12. The rail 11 is supported by two supporters 132 at two ends thereof and movably coupled to the bed 10 via the supporters 132. Below the rail 11, there is positioned a paper holding plate 131 for urging the paper to be cut against the bed 10 so as to facilitate the cutting operation. The motion of the paper holding plate 131 is controlled by a link structure 133 mounted onto one of the supporters 132. The link structure 133 includes a movable member 1331, a link 1332 and pins P1, P2, P3. For lifting up the rail 11, the movable member 1331 is turned on the pin P1 by the user, as indicated at 1331′. Hence, the pin P3 connected to the movable member 1331 moves along an arc locus L around the pin P1, as indicated at P3′. The link 1332 connected to the pin P3 will bring the pin P2 to the position of P2′. Therefore, the rail 11 led by the pin P2 is lifted up, as indicated at 11′. When the rail 11 is thus lifted up, the paper holding plate 131 also moves upwards since the paper holding plate 131 is coupled to the rail 11. After the pile of paper is put under the paper holding plate 131, the movable member 1331 is turned back to have the paper holding plate 131 move downwards to hold the paper on the bed 10. Since the paper holding plate 131 moves downwards to press the paper with the downward movement of the rail 11, slightly horizontal shift of the paper holding plate 131 is substantially conducted due to the slantingly movement of the link 1332 rather than exactly vertical movement relative to the paper. Accordingly, the topmost sheets of paper may be pushed away from the pile of paper due to the horizontal shift of the paper holding plate 131. Moreover, the link structure is too complicated to be assembled simply and conveniently so as to be disadvantageous to the assembling time and production cost.